.container {
  width: 400px;
  height: 500px;
  border: 1px solid #000;
  margin: 0 auto;
  overflow-y: scroll;
  position: relative;


}
.list-phantom{
    position: absolute;
    top: 0;
    left: 0;
    right: 0;

}
ul {
    list-style: none;
    margin: 0;
    padding: 0;
}
li {
    height: 50px;
    border: 1px solid #cfcfcf;
    box-sizing: border-box;
    text-align: center;
    line-height: 50px;
}
